This summer, we are following LSU researchers into the field as they collect data from all over the world, from the Mississippi River Delta Front in the Gulf of Mexico, to Borneo, to the South China Sea. Fearless explorers from the College of Science are charting new territories, finding new species, learning more about the properties of the seabed, and more.
This summer, Hollis Jones, a graduate student working with assistant professor of Biological Sciences Morgan Kelly, is traveling to multiple spots around Louisiana to collect and sample oyster tissue samples to investigate how oysters respond to environmental stressors. We asked Hollis to tell us more about her experiences with oysters in the field!
LSU College of Science: Why are you going into the field? What research questions are you trying to answer, or what data will you be trying to collect?
Hollis: We went out to Sister Lake, Louisiana this April to take oyster tissue samples for RNA sequencing. RNA is genetic material that carries instructions from DNA to control the synthesis of proteins. By looking at RNA in an organism at a given time, we can discover which genes were being expressed. We take the tissue samples on the boat because expression can change in a matter of minutes, and we want to know what these oysters are experiencing in the wild, that might cause them to express certain genes.
One of the main goals of my thesis is to find reliably expressed biomarkers of resilience in the eastern oyster transcriptome that can be used to assess the stress levels of wild oyster populations.
We also took around 100 of these oysters back to LSU's campus and 24 of them are currently residing in the basement of the Life Science Building! We are exposing these guys to combined temperature and salinity (salt) stress.
LSU College of Science: What do you expect to find?
Hollis: The eastern oyster has an extensive range and can tolerate a wide range of temperatures and salinities. Their genome reflects this by having an enriched number of genes related to protein folding [which is affected by heat], apoptosis, anti-oxidation, and the immune response. As the waters approach 35°C in late July and August, we expect to see up-regulation of these genes. While exploring these oysters' transcriptome we hope to find genes that are expressed early on in the oyster stress response - aka before the oysters start to die.
LSU College of Science: What will you bring with you into the field?
Hollis: Oysters in this area live on a soft muddy bottom, so we bring a dredge, which is kind of like a basket we can drag in the mud and then pull up onto the boat. Once we pull the oysters up we need to get rid of some of the epiphytes that grow on oysters, like mussels and barnacles, so we bring a small hatchet. We then put the oysters coming back to campus with us in a very fancy burlap sack.
We use an oyster knife to open the oysters that we take on-site tissue samples from. It's really hard to create sterile conditions on a rocking boat out in the Louisiana wetlands, but we do our best by bringing plenty of alcohol and gloves. Before we go out on the boat I prep all of the tubes we will need so that we can just quickly take a tissue sample and drop it into a tube. This will preserve all of the RNA in the tissue at the time of sampling so that we can analyze it later in the lab. One of the perks of working with oysters is that they’re delicious. After we take the tissue sample we’re done with the oyster, and they make a great snack #sampleyoursample!
LSU College of Science: What does it LOOK like to be in the field, for you? What do/did you eat, wear, etc.?
Hollis: When we’re out on the boat the sun can be pretty brutal, so rash guards, hats, and sunglasses are all critical. I probably ate about 15 oysters the last time we went out so I wasn’t even hungry for the steamy hot peanut butter and jelly that I’d packed!
There are three main marsh grasses that you see out in the Louisiana marsh (Spartina, Phragmites, and Juncus) and all the colors combined create a beautiful depth. There are also plenty of seabirds such as pelicans and terns that can make it pretty loud. When we pull the oysters out there are also often blue crabs, oyster drills (predatory snails), and polychaetes.
LSU College of Science: What is/was your favorite part about this field experience? What was most challenging?
Hollis: My favorite part of field work is the boat ride. Although it can be a little depressing to see how many houses have started to fall into the water because of erosion, looking out over the marsh is so relaxing. We also often see dolphins, and nothing makes your day like seeing a dolphin!
LSU College of Science: What was the most surprising or interesting thing that happened during your field experience?
Hollis: Apart from the pure elation at seeing a dolphin, the most surprising thing to me was seeing just how much life grows on the physical oyster shells. Oysters are considered ecosystem engineers because they are often the only hard substrate around that other organisms can hide in or settle onto. There are lots of mussels, bryozoans, barnacles, and seaweed!
LSU College of Science: What did you find? What kind of data did you collect? Did you answer any outstanding research questions or find anything related to your research project? Did you learn anything new?
Hollis: Aside from taking the tissue samples, we also measured the oyster length and took about 100 oysters back to our wet lab facilities on LSU’s campus so that we could expose them to combined temperature and salinity (salt) stressors and then measure respiration, clearance rate, condition index, and make histology comparisons. These physiological measurements combined with our genetic data will help us make connections between gene expression and phenotype.
LSU College of Science: What was most rewarding about this field experience?
Hollis: Going out on the boat with Dr. Jerome La Peyre and my lab mate Scott Riley was really fun. Research is a team effort and I am lucky to be able to work with such dedicated scientists.
LSU College of Science: What's next?
Hollis: The tissue samples are currently residing in a -20° C freezer for later analysis using qPCR but the other 90+ oysters are alive and stressed on campus!